In various agglomerates, such as paint, enamel, ink, synthetic resins, natural resins, pastes, etc., two or more substances constitute the mass. In manufacturing mixtures, while the substances may be churned in one container, it has been found that various portions of one or more of the substances maintains its separate identity in spite of being in apparent mixture. Pigment, such as carbon black, for example, when introduced into other substances resists integrating contact, such as with paint.
The vehicles, pigments and other things, such as dry lubricants like stearate of lead, maintain attachment among themselves and have boundary layers and surface tensions which resist connecting contact with other substances. Thus various degrees of mixture are encountered in the case of particle-to-particle interconnection which resists complete mutual dispersion. For example, to make gray paint, carbon black is introduced. If the carbon black is not thoroughly dispersed in the paint, the gray paint will be one shade in the can and an entirely different shade when applied with a brush, roller or gun because the application produces friction and shear which drives the pigment particles from attachment among themselves and forces them into dispersion with the paint by breaking down the boundary layers and surface tensions of both the pigment and the paint particles.
Various types of equipment have been used in the prior art to disperse the substances of conglomerates into one another in fine grain connecting contact such as drums rotating on a horizontal axis and having steel balls inside to tumble through the mass to effect dispersion. Also sand barrels on a vertical axis have been employed where the substances are forced through the sand while agitators rotate in the sand and agglomerate to drive the substances into contact with one another. Both such devices are slow, difficult and expensive to operate, and exceedingly difficult to clean and maintain.